Relative age techniques applied on alluvial fan surfaces to determine debris flow susceptibility, Mendoza province, Argentina

MOREIRAS, S.; E. MARTINEZ CARRETERO

GEOMORPHOLOGY

Elsevier

Año: 2005

0169-555X

The aim of this study was to determine debris flow susceptibility by application of relative dating techniques in six alluvial fan systems located along the Mendoza river valley as this kind of events are the most frequent and hazardous in this arid region. Soil development, rock varnish development, weathering degree, lichenometry and plant development were considered. According to our results, rock varnish and soil development were the most useful parameters to determine stability degree and debris flow susceptibility. Also, changes in soil properties indicated by the presence or absence of the B horizon, its thickness, and carbonate content were clear indicators of stability. Weathering degree was less convenient; nevertheless, disintegration and amount of broken boulders, which decrease on lower susceptibility surfaces, showed significant differences by ANOVA analyses. Presence of crustaceous lichens was also a good indicator of the stability degree; but this technique may be more controversial. Moreover, plant cover increased on stable surfaces, although the number of species did not.